title: Measurement of the strength of iodine-125 seed moving at unknown speed during implantation in brachytherapy.
abstract: The aim of this study is to demonstrate the feasibility of estimating the strength of the moving radiation source during patient implantation. The requirement for the counting time was investigated by comparing the results of the measurements for the static source with those for the source moving at 2, 5, 10 and 20 cm s(-1). The utilized source was (125)I with an air-kerma strength of 0.432 U (μGym(2)h(-1)). The detector utilized was a plastic scintillation detector (8 cm × 5 cm × 2 cm in thickness) set at 8 cm away from the needle to guide the source. Experiments were conducted in order to determine the most desirable counting time. Analysis using the maximum of the measured values while the source passed through the needle indicated that the results for the moving source increased more than those for the static source as the counting time decreased. The combined standard uncertainty, with the coverage factor of 1, was within 4% at the counting time of 100 ms. This investigation supported the feasibility of the method proposed for estimating the source strength during the implantation procedure, regardless of the source speed. The method proposed is a potential option for reducing the risk of accidental replacements of sources with those of incorrect strengths.
authors.affiliation: Department of Medicine, Graduate School of Sapporo Medical University, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Satoru
authors.initials: S
authors.lastname: Endo
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Tateoka
authors.forename: Osamu
authors.initials: O
authors.lastname: Asanuma
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Kamo
authors.forename: Kaori
authors.initials: K
authors.lastname: Sato
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Takeda
authors.forename: Masaru
authors.initials: M
authors.lastname: Takagi
authors.forename: Masato
authors.initials: M
authors.lastname: Hareyama
authors.forename: Jun
authors.initials: J
authors.lastname: Takada
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000032:analysis* / Q000627:therapeutic use; D009038:Motion; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007457:Iodine Radioisotopes
keywords: 125I; brachytherapy; moving source; source strength